Continuous use of block heaters

Always use golden rods inside the electronics console on the flybridge. Not sure how well they would work in a large engine room, My chiller system can make a bit of condensation and have been using a small fan at the dock to keep dry. Also use the vent covers depending on weather, which helps a lot, especially in the winter. Still using small ceramic heaters during the winter in the er, but considering changing to the oil pan heaters like SeaEric's 24/7/365.

I proved to my self a trouble light worked great. When I discovered the heated rod, I knew I was in heaven.
There cheap, give a couple a try. You will be amazed.

I have often argued the point of engines sitting and only running them a few minutes a month.
It warms the engine up enough to cool and condense more water.
It never gets hot enough to expel any water from the last dock run.
Cast iron heats up and cools off slower than anything else around it, including mother nature.
A cooling block will draw in moist air in.
Exhaust valves and valve seats exposed to the air will rust and fail. Seen it a few times.

So keep the block temp constant, not hot or real warm, lukewarm and constant.
Not much required for this.

A properly inflated ball or fender in the exhaust helps also.

When I pickle for the winter I block the exhausts with plastic pails, and the inlets with thick garbage bags around the air seps. But, intuitively, I think the engine heaters do the must good. I winter in the water so I also do not get big swings in temp in the engine room. In the salon yes, but not near the water line. I have small oscillating fans also to move the air, both in the ER and salon.

Most stationary emergency generators have continuous heaters because they start up with the throttle against the governor. If the engines were cold they would pull the pistons into in short order, but they don't have salt water sitting inside them to evaporate and leave salt in the system.

You brought up a subject that is more fact than theory. A wet exhaust is like an air pump every time air pressure changes, wave action, or temp changes it is pumping air and moisture. Underwater exhaust is by far the worst. Block heaters or oil pan heaters are pretty much it, short of heating the engine room to high temps. Like the oil pan heaters such as SeaEric uses, simple and not immersed in the coolant. He also uses them 24/7/365 for about 8 years, so they must be durable. Personally I would use a higher wattage to get the engine temp up high enough to cover the wet exhaust moisture in the cylinders you mentioned. The bonus is taking care of high humidity and condensation in the er, better for electricals and corrosion. It would be great if all we had to do is run the engines every two weeks, but I still like having a dry er.

A pic while of our underwater exhaust while doing some exhaust work.That is the water level at the bottom of the fiberglass tube.Every time the boat rocks it pumps moist air towards turbo, valves, and cylinders with open valves.

THIS, just run the engines every 2 weeks for 45 minutes. It circulates the oil and everything from the valve train down and cylinder walls get a coat. I run them for about 30 minutes at idle, then I bring them up to around 1600 rpms to get the turbo's spinning a little for a few minutes......then I bring them down to idle and bump each on in gear a couple of times, to circulate the clutches in the gear...….let idle a few mins and shut down...….EGT's get to 400-440 rpms doing this and burn out any moisture. Never an issue.

Where does the water go ??? That is just a 38 watt heating element . 1 watt equals 3.412 btu so that unit adds ~130 btu's of heat a hour. Warm/Hot air holds more moisture/ humidity

In the NE, if you're pickled and store in the water, running the engine is not an option. Essentially the blocks sit there for 4-5 months unless you do something static like block air inlets and warm the blocks.

It does not take much, sometimes a couple of them.
Don't need to keep things hot, just not to let get to cool and aid condensation.
Just a lil heat helps starting and wont let anything freeze.

If's it's that cold, you already blocked the vents.

I agree. But the Origional Poster is not in the NE and his engine is not pickled.

Tampa it looks like. I was just commenting on the poor plight of we boaters in the NE.

I had a gas I/O boat (long ago) and one year the deck was covered in ice and snow for a few days. Lil trouble light kept the engine toasty and the doghouse clean.